Visibility Sampling

2. The apparatus of claim 1, further comprising sampling logic, implemented at least partially in hardware, configured to, when the flow tracking unit indicates that a particular packet is the first packet in a new flow, send a diagnostic data unit comprising at least a portion of the particular packet to a collector.

4. The apparatus of claim 1, wherein the plurality of the packets that is inputted into the flow tracking unit is a set of packets that have experienced a particular type of visibility event while being processed by the apparatus.

5. The apparatus of claim 1, wherein the flow tracking unit further includes flow size counters and logic, implemented at least partially in hardware, configured to increment a counter, of the flow size counters, that is associated with the packet information of the packet, wherein the counter indicates a current size of a flow associated with the packet.

8. The apparatus of claim 1, wherein the one or more particular events in response to which the flow state reset logic is configured to reset the memory entries include: a passing of an amount of time, exiting a high delay state, receiving a certain number of packets since entering a high delay state, or completion of sending a snapshot of contents of a queue of the packets.

11. The apparatus of claim 1, wherein the packet information is a set of header fields in the packet, wherein determining the identifiers comprises calculating the identifiers using hashing functions on the packet information, each of the flow tracking identifier generators executing a different hashing function.

13. The method of claim 12, further comprising, responsive to determining that a particular packet is the first packet in a new flow, sending a diagnostic data unit comprising at least a portion of the particular packet to a collector.

17. The method of claim 12, wherein the one or more particular events include one or more of: a passing of an amount of time, exiting a high delay state, receiving a certain number of packets since entering a high delay state, or completion of sending a snapshot of contents of a queue of the packets.

18. The method of claim 12, wherein determining the identifiers comprises determining each identifier of the identifiers using a different mapping mechanism, each mapping mechanism associated with a different memory bank, in which any memory entries corresponding to identifiers generated by the mapping mechanism are located.